1. Field of Invention
Exemplary aspects of the present invention relate to an optical assembly including a liquid crystal element and another optical modulation device, and to a projector assembled with such an optical assembly.
2. Description of Related Art
A related art projection type liquid crystal display apparatus includes a liquid crystal display element for optical modulation, an incident side polarizing plate disposed on the incident side of the liquid crystal display element, an emission side polarizing plate disposed on the emission side thereof, and a pair of optical compensation elements one of which is disposed between the liquid crystal display element and the incident side polarizing plate, and the other of which is disposed between the liquid crystal display element and the emission side polarizing plate (see JP-A-2002-182213). In this related art projection type liquid crystal display apparatus, the optical compensation elements paired are each made up of a wide view film (hereinafter “WV film”) and each rotatable within a plane perpendicular to an optical axis. Thus, both WV films are appropriately rotated to accurately align the directions of their optical axes with a rubbing direction of the liquid crystal display apparatus, thereby compensating a phase difference that remains on the incident and emission sides when an electrical field is formed in a liquid crystal layer, thus enabling an enhancement in black level display.
However, when the WV film is disposed on the incident side of the liquid crystal element as in the above projection type liquid crystal display apparatus, the WV film is exposed to strong illumination light, so that its characteristics gradually deteriorate due to a change with age. Particularly, when ultraviolet light is included in the illumination light, the WV film undergoes significant deterioration, so that there arises the need to replace the WV film earlier in order to maintain the image quality of a projected image.
In a color display type projector, for example, a cross dichroic prism is disposed on the emission side of the liquid crystal display element. However, because of the cost of such a cross dichroic prism and a limitation in the back focus of a projection lens, a space for assembling the WV film, the polarizing plate, etc. cannot be sufficiently ensured between the liquid crystal display element and the cross dichroic prism. Consequently, the WV film, the polarizing plate, etc. come into a close-packed state and thus become insufficiently cooled, or as regards the WV film on the emission side, it is obliged to omit the system of adjusting the rotational position thereof.
Accordingly, exemplary aspects of the invention provide an optical assembly capable of enhancing black level display while reducing or preventing deterioration of a WV film, and a projector assembled therewith.
Exemplary aspects of the invention provide an optical assembly in which the WV film can be appropriately rotated even when a color combining optical system is disposed on the emission side of a liquid crystal display element, and a projector assembled therewith.